1. Field of the Invention
This invention relates to a manually operated pencil sharpener and particularly to a mechanical pencil sharpener having a slidably rotatable cutter assembly which is activated by the manual force associated with the insertion of a pencil therein.
2. Description of the Prior Art
Manually operated pencil sharpeners are well known. For example, there are the simple blade types or those where a cutter assembly is rotated via gearing, a crank or handle. In order to sharpen a pencil in these types of devices, the operator must hold the pencil in one hand and crank the handle of the pencil sharpener with the other hand or the operator manually rotates the pencil (or sharpener) about its longitudinal axis within a cutter assembly. In general, these types of sharpeners must by clamped, bolted or otherwise affixed to a stable substrate (making them a permanent, non-portable fixture). Other types of manually operated pencil sharpeners having rotatable cutting assemblies are shown in U.S. Pat. Nos. 1,182,327 and 2,470,387. For example, U.S. Pat. No. 1,182,327 teaches a pencil sharpener having two symmetrical knife carrying frames with helically bent cutting blades mounted to a spirally threaded stem. A thumb-nut is threaded on the stem which, when forced down the stem by the action of fingers, forcibly rotates the stem and the cutting frames of the pencil sharpener.
Motor-driven sharpeners with separate starting switches are also well known. These motor-driven pencil sharpeners operate on live current or are battery powered. However, they require costly electrical energy and have unattractive cords which are potentially hazardous. The cordless type, such as battery-powered sharpeners, have the disadvantage of requiring frequent changes of batteries.